<nz-upload [(nzFileList)]="fileList" [nzBeforeUpload]="beforeUpload"  
     nzListType="picture" (nzChange)="nzChange($event)">
    <button nz-button><i nz-icon nzType="upload"></i><span>上传文件</span></button>
  </nz-upload>
  <button
    nz-button
    [nzType]="'primary'"
    [nzLoading]="uploading"
    (click)="handleUpload()"
    [disabled]="fileList.length == 0"
    style="margin-top: 16px"
  >
    {{ uploading ? '上传中' : '开始上传' }}
  </button>